It is now commonplace for political discourse, news reports, and popular fictions to draw on themes of political violence and threats to national and individual security as mechanisms for the perpetuation of fear. Stories (whether fictive or factual) of terrorism, crisis, surveillance, racial stereotyping, and the fallibility of law have become a very real part of the mediated experience of fear for the public, and they provoke a number of questions surrounding complex issues of protectionism, identity, trust, and the conflation of law and justice. It has been argued that such stories are constructed and utilized by key decision-makers as effective politicking in order to promote protectionist policies and activities. In recognizing that this "politics of fear" rests upon public assumptions and beliefs concerning safety and risk, it is important to understand how a public experience of fear is actually expressed and constituted in the public imaginary. Using social media as an interesting lens through which we can understand how fear is defined and realized in everyday social interaction, the paper will demonstrate that in times of high alert Twitter provides access to an articulated experience of fear. This paper will qualitatively explore the co-production and (re)circulation of these assumptions and beliefs through one particular story: the "Sydney Siege" hostage event of December 2014. By focusing on the Twitter response to this event, the paper provides an empirical account of public critique of law's justice narrative through the emotional experience and expression of fear. Drawing on critical content analysis and the Aristotelian discourse analysis method, the paper illustrates the complicity of social media, emotion and a prevalent rhetoric of fear in the reinforcement of law's justice narrative during times of high alert or crisis.